The group of international experts in gestational diabetes spent almost two years determining how to apply findings from a 2008 study, also led by Metzger, that found a much lower level of a pregnant woman's blood sugar than previously believed increased the risk of serious complications.

The researchers set their new diagnosis and treatment criteria by determining the blood sugar level that nearly doubled the risks to the baby and mother.

"This study says these risks to pregnancy are like many things we deal with in medicine," Metzger said. "The risk of having a stroke doesn't begin when your blood pressure is 140 over 80. That's when we say you have hypertension, but that's not where the risk begins to affect your health. That starts sooner. A similar situation is how your cholesterol level relates to the risk of having heart disease. It doesn't begin at 200. That's where it reaches the threshold where common treatments can reduce the risks."

"Our research represents an examination of risks and a consensus about how high a level the risk needs to reach before a diagnosis should be made and treatment should be considered," Metzger said.

For the past decade, the rate of gestational diabetes as previously measured has soared as much as 50 percent. "We shouldn't be surprised," Metzger said. "The fact that we have a lot of gestational diabetes to deal with is consistent with the major impact that diabetes and obesity are having in our population at large. How could we expect pregnancy to escape that?"

The 23,000 women were part of the Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) project, which began in 1999.

Source: Northwestern University